The GMR Switch Advantage

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Arthur White
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2 SENSOR PRODUCTS DIVISION The GMR Switch Advantage GMR Switch = Larger Design Margin When GMR materials are integrated with digital on-board electronics, the result is the GMR Switch. The GMR Switch offers unmatched high performance and flexibility in magnetic field sensing. Range of Operation (Oersteds) HALL AMR GMR Switch The GMR Switch will accurately and reliably sense magnetic fields, with less error than any other magnetic sensor on the market today. In addition, there is minimal shift in the magnetic field operate point of the GMR Switch over both voltage and temperature extremes. This gives the manufacturer the ability to make a high precision, high tolerance magnetic sensing assembly. The GMR Switch is the clear choice when a digital output signal is required of a magnetic field sensor. Total Available Design Margin GMR Switch Magnetic The GMR Switch operates over a wide range of magnetic fields. Hall GMR Switch AMR Sensor + Magnet + Mechanical Mechanical Typical Operate Point Error Band (%) 4.5 to 30 VDC -40 to +125 C The GMR Switch features a smaller error band than any other magnetic sensor on the market. 2

3 AD SeriesGMR SwitchTM GMR Switch Products Selection Guide Output Type, Available Regulator NVE's GMR Switch is available in a wide range of packaging, output type, and magnetic trigger field varieties. The purpose of this application note is to explain the different output and packaging options as well as provide information on how to specify the correct part number when ordering. All NVE GMR Switch product part numbers follow the same general form. As shown in Figure 1 the first x in the part number ADxxx xx specifies output type, the next two x s specify trigger field and direction of sensitivity, and the last pair specify the package type. The following three sections define these numbers in detail. Figure 1 ADxxx xx The first numeric digit of the part number ADxxx xx specifies the output type, and the availability of a regulated voltage supply on a separate pin. The following four output types are available: 20 ma Current Sink 20 ma Current Source Separate 20 ma Current Sink & 20 ma Current Source Two Separate 20mA Current Sinks All of these outputs turn ON when the magnetic field is applied. (In some situations, it may be desirable to have an output that turns OFF when the magnetic field is applied. While such a sensor is not available as a standard product, it could be available as a custom product; please consult NVE.) Some of NVE's GMR Switch products also feature a regulated supply voltage available external to the part, on a separate pin. This regulator provides a 5.8V reference capable of supplying up to 3 ma of drive current. This regulated output may be used to run an LED or any other low power device. Output Type and Available Regulator Package Type The following table defines the first digit in the AD part number. Trigger Field and Direction ADxxx xx Number Meaning 0 20 ma Current Sink 1 20 ma Current Source 2 Separate 20mA Current Sink and 20mA Current Source 3 Two Separate 20mA Current Sinks 4 20 ma Current Sink + External Regulated Voltage 5 20 ma Current Source + External Regulated Voltage 6 Separate 20mA Current Sink and 20mA Current Source + External Regulated Voltage 7 Two Separate 20mA Current Sinks + External Regulated Voltage 3

4 SENSOR PRODUCTS DIVISION Magnetic Trigger Field and Direction of Sensitivity The second and third numeric digits of the part number (ADxxx xx specify the magnetic trigger field and direction of sensitivity of the part. Four different magnetic trigger fields are available for the GMR Switch Products: 20 Gauss (20 Oersted, 2.0 mtesla, 1.6 ka/m) 28 Gauss (28 Oersted, 2.8 mtesla, 2.23 ka/m) 40 Gauss (40 Oersted, 4.0 mtesla, 3.2 ka/m) 80 Gauss (80 Oersted, 8.0 mtesla, 6.4 ka/m) Other magnetic trigger field levels, from 10 Gauss to 250 Gauss, are available on a custom basis; please consult NVE. The following table defines the second and third digits in the AD part number: ADxxx-xx Number Meaning Gauss, Standard Direction of Sensitivity Gauss, Standard Direction of Sensitivity Gauss, Standard Direction of Sensitivity Gauss, Standard Direction of Sensitivity Gauss, Cross Axis Direction of Sensitivity Gauss, Cross Axis Direction of Sensitivity Gauss, Cross Axis Direction of Sensitivity Gauss, Cross Axis Direction of Sensitivity Package Type NVE GMR Switch products are available in two different packages: an SOIC small outline package, and a TSSOP ultra-small outline package. GMR Switch products are not available in die form; however, NVE is able to do chip-onboard assembly in cases where GMR Switch products must be placed on extremely small PCBs, and the TSSOP package is too large; please consult NVE on these applications. In addition, custom package modifications are available; please consult NVE for details. The following table defines the last two digits in the AD series part number: ADxxx xx Number Meaning -00 TSSOP Package -02 SOIC Package This part numbering system allows for 128 different products based on the GMR Switch. Since it is impractical for NVE to stock all 128 different products, not all part numbers are available from inventory. In order to serve the broadest possible customer base, NVE stocks many of these part numbers. If a part is not currently in inventory, a six week lead time for delivery is required. In some cases, minimum order quantities apply. AD Series Pin Configurations Two directions of sensitivity are available with all parts. "Standard" direction of sensitivity is defined as the direction parallel to the edge of the package containing the pins. "Cross Axis" direction of sensitivity is defined as the direction perpendicular to the edge of the package containing the pins. N/C VCC VCC Sink(1) Source N/C* Source N/C Sink(2) Vregulated Sink(2) Cross Axis Vregulated Ground Sink(1) 1 N/C Ground Package Marking: All SOIC packaged parts (-02 part number suffix) are marked with the correct part number on the package. Due to the limited space available on the TSSOP package (-00 part number suffix), these parts are marked with a code. See NVE for code information. Note 1 : In the case of a standard axis part with the Vregulated pin option, Sink(1) will appear at the pin labelled N/C*. 4

5 AD SeriesGMR SwitchTM Magnetic Characteristics Magnetic Specifications are listed for the minimum and maximum ranges over temperature and voltage Nominal Minimum Maximum Minimum Maximum Operate Point Operate Point Operate Point Differential (1) Differential (1) (Oersteds) (Oersteds) (Oersteds) (Oersteds) (Oersteds) (2) (2) Absolute Maximum Ratings Parameters Symbol Min. Max. Units Supply Voltage V CC 33 Volts Reverse Battery Voltage V RBP -33 Volts Current Sinking Output Off Voltage 33 Volts Current Sourcing Output Off Voltage 0 Volts Current Sinking Reverse Output Voltage -0.5 Volts Current Sourcing Reverse Output Voltage -0.5 Volts Continuous Output Current I O 24 ma Operating Temperature Range T A (3) o C Storage Temperature Range T S o C Magnetic Field H Unlimited (4) Oersteds Electrical Specifications Electrical Specifications are T min to T max unless otherwise stated. Parameter Symbol Min. Max. Units Test Condition Supply Voltage (3) V CC V Operating Supply Current, Single Output GMR Switch I CC ma Output off V CC = 12V Current Sinking Output (2) I O 0 20 ma (5) Operating Current Sourcing Output (2) I O 0 20 ma (5) Operating Output Leakage Current I LEAK 10 µa Output off V CC = 12V Sinking Output Saturation Voltage V OL 0.4 V Output on I OL = 20mA Notes: Sourcing Output Saturation Voltage V OH V CC -2.5 V Output on I OL = 20mA Regulated Output Voltage V REG V Operating Regulated Output Current I REG 3.0 ma Operating 1. Differential = Operate Point-Release Point 2. Minimum release point = 5 Oe 3 Thermal power dissipation of the packages used by NVE is 240ºC/Watt for the SOIC package, and 320ºC/Watt for the TSSOP package. Figure 3 shows ambient temperature vs. supply voltage derating curves for both packages in free air, with a single output. Heat sinking parts by attaching to a PCB improves temperature performance. 4 There is no maximum field that will damage device. 5. Outputs must be current limited through a series resistor. Exceeding absolute maximum continuous output current ratings will result in damage to the part. Also, see Figure 2 for an output current derating curve. 6. If V CC 6.6V than V REG 5.8V. If V CC 6.6V than V REG V CC -0.9V. 5

6 SENSOR PRODUCTS DIVISION SOIC 8 package (4.90) All dimensions are typical unless otherwise stated Dimensions: inches (mm) (3.76) (5.99) NVE xxxxx xxx (3.91) (0.381) X 45 o (0.508) (4.77) (1.37) (1.55) (1.27) x (0.102) min (0.254) max TSSOP 8 Package All dimensions are typical unless otherwise stated (3.00) Dimensions: inches (mm) (3.00) (4.90) NVE xxx (3.00) (0.533) (3.91) (0.86) (1.02) (0.65) x (0.102) min (0.305) max 6

AD SeriesGMR SwitchTM Output Current Derating Curve 25 Maximum Output Current (ma) 20 ma Extends to 30V 20 15 10 4.5 6 7.5 9 10.

7 AD SeriesGMR SwitchTM Output Current Derating Curve 25 Maximum Output Current (ma) 20 ma Extends to 30V Figure 2 Supply Voltage (V) Operating Temperature Derating Curves for SOIC and TSSOP Packages in Free Air Temperature (C) SOIC TSSOP Supply Voltage (V) 50 Typical Operate Points (OP) and Release Points(RP) AD004 and AD005 Figure 3 Magnetic Field (Oersteds) Ambient Temperature = 25C AD004 OP AD004 RP AD005 OP AD005 RP Supply Voltage (V) Operate Point(OP) and Release Point(RP) Variation Over Temperature 50 Magnetic Field (Oersteds) VCC = 12V AD004 OP AD004 RP AD005 OP AD005 RP Temperature ( C) 7

GMR Switch Precision Digital Sensors

GMR Switch Precision Digital Sensors GMR Switch Precision Digital Sensors When GMR sensor elements are combined with digital on-board signal processing electronics, the result is the GMR Switch. The GMR